Process and apparatus for producing self-texturing fibers



Feb. 27, 1968 J. E. FRAZER 3,371,139

PROCESS AND APPARATUS FOR PRODUCING SELF-TEXTURING FIBERS Filed Dec. 22, 1964 INVENTOR. JOHN E. FRAZER Ha /5% I ATTORNEY United States Patent 3,371,139 PROCESS AND APPARATUS FOR PRODUCING SELF-TEXTURING FIBERS John E. lh'azer, Decatur, Ala., assignor to Monsanto i Company, St. Louis, Mo., a corporation of Delaware Filed Dec. 22, 1964, Ser. No. 420,276

Claims. (Cl. 264-171) ABSTRACT OF THE DISCLOSURE The present invention relates to self-texturing synthetic filaments composed of two or more spinning compositions having differential fiber shrinkage characteristics and more particularly to an improved method and apparatus for producing synthetic filaments having differential physical properties over the cross-section of theindividual filaments to facilitate self-imposed crimp when subjected to a heated environment.

Various methods and apparatus have been utilized to produce self-texturing synthetic filaments in an attempt to eliminate the additional mechanically imposed crimp ing process which is otherwise necessitated. The spinning assemblies used to perform the known processes have been complex and expensive to design and construct. For example, each spinning composition must be precisely delivered to the individual spinneret orifices by means of intricate passageways, or each orifice cavity is precisely split by a delicate septum designed to terminate at the spinneret opening to insure that the individual streams are maintained discrete from each other up to their point of extrusion. Other known conjugate spinning systems include means for spinning sheath-core filament structures by using concentric feeding means and laminated platetype mixers which are similarly expensive to design and -construct. The equipment for all of the above known systems is mechanically complex and difiicult to maintain.

With the foregoing in mind, a primary object of the present invention is to provide a simple, improved process and apparatus for producing potentially self-crimpable synthetic filaments.

Another object of this invention is to provide a-process for forming allcmating wedge-shaped segments of spinning compositions and extruding the alternating segments of spinning compositions to produce potentially self-- crimpable filaments.

Still another object of this invention is to provide a spinning assembly which may be selectively operated to produce self-crimping filaments having variable amounts of crimp per inch depending upon the selected operation.

The above objects and advantages have been accomplished by apparatus comprising in combination a pair of metering pumps for delivering at least two different spinning compositions to a pair of inlets in a housing having a two-way plug position therein for rotation to communicate with the inlets at alternate intervals during rotation of the plug at a constant rate to form alternate contiguous segments of the spinning compositions which are discharged to an enlarged cavity adjacent to an orificed plate where 3,371,139 Patented Feb. 27, 1968 the segments are deposited in wedge-shaped layers prior vironment suitable for developing the crimp. The plug is grooved around the circumference to provide limited communication between both inlets and the outlet so that a constant discharge pressure is maintained, the pressure being further regulated by a relief valve and recirculating means connected across each pump.

For a better understanding of the present invention reference is made to one possible embodiment which is illustrated in the accompanying drawing in which:

FIGURE 1 is a diagrammatical view of the overall system used for carrying out the invention;

FIGURE 2 a partial plan view showing a cross-section of the plug member aligned for communication with one source of spinning composition and the patterned effect imparted to two spinning compositions by rotating the plug at a constant speed;

FIGURE 3 is a pictorial view of the plug member illustrating the two-port arrangement and the circular groove;

FIGURE 4 is an exploded view showing how the plug. member is assembled in the housing; and

FIGURE 5 is a cross-sectional view of the plug member taken across the section 55 of FIGURE 3.

Referring to FIGURE 1 of the drawing, there is shown a typical arrangement of apparatus for producing potentially self-crimpable filaments in accordance with the present invention. In the arrangement illustrated, spinning compositions I0 and 12 are supplied from separate sources, not shown, and are uniformly delivered to a proportioning unit 14 by metering pumps 16 and 18, respectively. The proportioning unit 14 has a T-shaped configuration with a bore 20 extending through the central portion thereof. Metering pump 16 is connected to the proportioning unit 14 by an inlet pipe 22 which provides communication with bore 20 through an inlet passageway 24. Spinning composition 12 is delivered to the proportiontng unit 14 by metering pttmp 18 through inlet pipe 26 which communicates with bore 20 through an inlet passageway 28. A plug member 30'made from Teflon or a material having similar properties is mounted for rotation in bore 20 and connected to a speed changer 32. As illustrated in FIGURE 5 the plug 30 has a pair of ports counterbored in the side thereof at degrees apart to form a right angle passageway 34 through one quadrant of the plug. Referring back to FIGURE 1 the passageway 34 is aligned with inlet 24 and an outlet 36 for the discharge of spinning composition 10 through passagewavs 24. 34, 36 and discharge pipe 38 to a spinneret 40. FIG- URE 2 shows the plug 30 positioned for communication between inlet 28 and passageway 34 for conveyance of spinning composition 12 to the'spinneret 40.

For a better illustration of the proportioning element or plug 30. reference is made to FIGURE 3 which shows a groove 42 conncetingthe ports 44 and 46 around the circumference of the plug. The groove 42 is preferrably Ml inch wide and ,4 inch deep to provide continuous communication between inlets. 24, 26 and outlet 36 so that a uniform pressure is maintained at the spinneret. Another important result achieved by this particular design is the combined flow of the two compositions in stratified layers intermittently between the alternate slugs of compositions 10 and pattern as shown at 50 in FIGURE 2. Also there is a slight amount of randomness'introdueed by the fact that the plug 30 must rotate through a turn for transfer of one spinning medium and a l tlll'll for the other depend ing upon whether the plug is rotated clockwise or counter clockwise. To further establish a more uniform pressure 12 to produce a wedge-shaped 3 throughout the system a relief valve 52 is provided on the discharge side of metering pump 16 and a return line 54 connecting the relief valve to the suction side of the pump is provided for recycling the spinning medium back to the pump suction. A relief valve 56 and return line 58 are similarly provided for pump 18. The relief valves are selectively set to relieve the system pressure build-up caused by the restricted flow in groove 42 when the plug passageway 34 is not in alignment with either inlet 2-1, 28 and the outlet 36.

FIGURE 4 shows an erplodcd view of the individual parts required for assembling the proportioning element in the housing 60. The plug 30 is placed into bore 20 and a coil spring 62 is fitted in a recessed portion thereof for rotation which is facilitated by a bearing insert 64 seated in the recessed area against the Teflon plug. A screw threaded cap 66 is used to retain the plug and spring in housing 60. The plug has a shoulder 68 mounted in the end opposite cap 66 which extends beyond housing 60 for connecting the electrically driven speed changer 32.

The fibers 70 are spun in accordance with the invention when two spinning mediums are supplied to the proper tioning plug 30 which is rotated by speed changer 32 from 1 to 20 rpm. to sequentially align inlets 24 and 28 with outlet 36 whereby a patterned fiow of the spinning mediums having different compositions are advanced through discharge pipe 38 to spinneret-wand extruded to form potentially self-crimpable fibers.

The preferred rate of rotation of plug 30 is from 3 to rpm. since this rate produces the patterned effect which imparts an acceptable amount of shrinkage to the spun yarn or fabric after bulking has been accomplished.

Examination of the filaments spun in accordance with the present invention disclosed that the cross-sections are comprised of both compositions varying in different ratios that occur in long lengths with randomly occuring short portions that exhibit cross-sections comprised of a single composition.

It will be understood by those skilled in the art that the rate of rotating the plug 30 controls the patterning effect and thus determines the physical characteristics of the filaments formed.

For a better understanding of the invention, the following example is given to illustrate a preferred form.

Example A first polymer comprised of 93% acrylonitrile and 7% vinyl acetate was dissolved in N-N dimcthyl aceta mide solvent to form a 25% solids solution designated as Dope A. A second polymer comprised of 92% acrylonitrilc, 6% vinyl acetate, and 2% styrene was also dissolved in N-N dimethyl acetamide to form a 23% solids solution designated as Dope B.

Both dopes were continuously metered at a rate of736 cc./min. while the proportioning element was rotated at 3 rpm. The segmented Dope stream being discharged from the element was extruded through a spinning jet having 20,000 holes 3 mils in diameter, and the extruded filaments were coagulated in a bath comprised of 57% solventand.; t31% -water at a temperature of 43", ,C;.Ihe

fibers produced were washed and stretched 4.5 times- -in.

boiling water before being passed through a'finish bath and thereafter were dried and crimped.

The physical appearance of the fibers after crimping was not different from conventional single component fibers, i.e., the fibers displayed the conventional saw tooth configuration typical of mechanical crimping. The crimpcd fibers were then exposed to saturated steam under 30 p.s.i.g. pressure. During the steam treatment, the fibers developed additional crimp of a random 'hclical configuration which imparted a wool-like hand and appearance to the fiber.

Since it is apparent that many changes and modifications can be made to the embodiment illustrated and described herein without departure from the nature and scope of the present invention, it is to be understood that the invention is not to be limited except as set forth in the appended claims.

I claim:

1. A method of producing potentially self-crimpablt filaments comprising the steps of conveying at least twc spinning mediums having different compositions to a junction, continuously discharging a portion of each spinning medium simultaneously to form discrete layers to provide continuous communication past said junction, alternately discharging the remaining portion of each spinning medium being conveyed to said junction to form wedge-shaped segments, and advancing the combined spinning mediums to an extrusion point.

2. A method of producing potentially self-crimpablc continuous filaments in a spinning system comprising introducing two differently characterized spinnable fiberforming materials to a common junction transmitting a portion of each material past said junction simultaneously to form discrete layers whereby uninterrupted feeding is provided, sequentially transmitting the remaining portion of each material in the form discrete predetermined segments to an extrusion point, and maintaining a uniform pressure on the fiber-forming materials throughout the system.

3. A method of producing potentially self-crimpable continuous filaments in a spinning system comprising introducing two spinnable fiber-forming materials to a proportioning element, said materials having differential shrinkage properties, transmitting a portion of said materials past the proportioning element simultaneously in equal proportions to form discrete layers having planar interfaces, rotating the proportioning element to sequentially transmit the remaining portion of each material in the form of discrete predetermined segments to an extrusion point, and maintaining a uniform pressure on the fiber-forming materials throughout the spinning system.

4. Apparatus for producing self-texturing continuous filaments comprising, in combination, means for delivering at least two fiber-forming materials from different sources to a proportioning unit having plural inlets and a single outlet, a plug member positioned in the proportioning unit for rotation, a pair of connecting ports in said plug member, means for rotating the plug member to sequentially align each inlet with the outlet, a groove circumscribing the plug member to provide continuous communication between the inlets and the outlet, and a spinneret connected to the outlet for producing continuous filaments.

5. Apparatus for producing self-texturing fibers comprising, in combination, a housing having plural inlets and an outlet, a metering pump connected to each inlr for delivering a fiber-forming material from differer sources to said housing, a plug member positioned in th said housing, said plug member being the frustum of cone and having a pair of interconnecting ports in or quadrant thereof, means for rotating the plug .at a corstant speed to sequentially align the interconnecting par-- with one inlet and the outlet, a rectangular groovc ci cumscribing the pliigto'connect'the interconnecting por with both inlets and the outlet whereby a uniform pre sure is maintained against a spinneret positioned downstream from =stlitt'plug to produce constant denier continuous filaments having self-crimping potential.

References Cited UNITED STATES PATENTS ALEXANDER H. BRODMERKEL, Primary Examiner.

l. H. WOO, Axis/an! Examiner. 

